Tea consumption and cognitive impairment and decline in older Chinese adults

Background: Laboratory research suggests that tea has potential neurocognitive protective effects, but this is not established in humans. Objective: We aimed to examine the relation between tea intake and cognitive impairment and decline. Design: Among community-living Chinese adults aged >= 55 y in the Singapore Longitudinal Ageing Studies cohort, we measured tea consumption at baseline and administered the Mini-Mental State Examination (MMSE) at baseline and 1-2 y later. Cognitive impairment was defined as an MMSE score <= 23 and cognitive decline as a drop in MMSE score of >= 1 point. We performed cross-sectional analysis of baseline data from 2501 participants and longitudinal analysis of data from 1438 cognitively intact participants. Odds ratios (ORs) of association were calculated in logistic regression models that adjusted for potential confounders. Results: Total tea intake was significantly associated with a lower prevalence of cognitive impairment, independent of other risk factors. Compared with the ORs for rare or no tea intake, the ORs for low, medium, and high levels of tea intake were 0.56 (95% CI: 0.40, 0.78), 0.45 (95% CI: 0.27, 0.72), and 0.37 (95% CI: 0.14, 0.98), respectively (P for trend < 0.001). For cognitive decline, the corresponding ORs were 0.74 (95% CI: 0.54,1.00), 0.78 (95% CI: 0.55, 1.11), and 0.57 (95% CI: 0.32, 1.03), respectively (P for trend = 0.042). These effects were most evident for black (fermented) and oolong (semi-fermented) teas, the predominant types consumed by this population. In contrast, no association between coffee intake and cognitive status was found. Conclusion: Regular tea consumption was associated with lower risks of cognitive impairment and decline.